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MEDSCI 142 > Section 2: Autonomic and Endocrine System > Flashcards

Section 2: Autonomic and Endocrine System Flashcards

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1
Q

Organisation of nervous sytems: CNS and PNS

A

CNS:
Brain
Spinal cord

PNS:
Cranial nerves
Spinal nerves
Ganglia
Peripheral nerves
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2
Q

Sensory vs motor neurons

A

Sensory neurons: afferent, carry into body
Motor neurons: efferent, carry away from body. Multi-polar in structure

Via cranial and spinal nerves

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3
Q

Types of motor (efferent) neurons

A

Somatic (voluntary) –> Skeletal muscle

Autonomic (involuntary) –> Sympathetic or parasympathetic –> cardiac muscle, smooth muscle, glands

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4
Q

The alarm response

A

Increased heart rate and force of contraction
Dilation of pupils
Decreased salivation
Dilation of bronchi –> breathe faster
Contraction of arrector pili muscles and increased secretion from sweat glands (skin)
Constriction of blood vessels, especially in skin
Decreased digestion (gut)
Increased blood sugar, blood pressure (liver) and water retention (kidneys)

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5
Q

The relaxation response

A

Decreased heart rate and force of contraction
Contraction of pupils
Increased salivation
Constriction of bronchi –> breathe slower
Dilation of peripheral blood vessels (skin)
Increased digestion (gut)

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6
Q

Autonomic Nervous System (ANS)

A

Controls body’s internal response

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7
Q

ANS - Sympathetic division

A

Responses associated with exercise, emotion, excitement

Alarm response

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8
Q

ANS - Parasympathetic division

A

Responses associated with repletion, rest, relaxation

Relaxation response

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9
Q

ANS: Autonomic vs somatic - sensory input

A

Autonomic: Mainly interoceptors (internal sensing)

Somatic: Special senses and somatic senses

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10
Q

ANS: Autonomic vs somatic - control of output

A

Autonomic: Involuntary from limbic system, hypothalamus, brain stem and spinal cord

Somatic: Voluntary from cerebral cortex (outer cortical brain)

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11
Q

ANS: Autonomic vs somatic - motor neuron pathway

A

Autonomic: Two-neuron pathway (pre-ganglionic and post-ganglionic)

Somatic: One-neuron pathway

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12
Q

ANS: Autonomic vs somatic - neurotransmitters

A

Autonomic: Acetylcholine
- Pre-ganglionic axons
- Post-ganglionic parasympathetic
- Post-ganglionic sympathetic to sweat glands
Autonomic: Norepinephrine
- Post-ganglionic sympathetic fibres other than to sweat glands

Somatic: Acetylcholine

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13
Q

ANS: Autonomic vs somatic - effectors

A

Autonomic: Smooth muscle, cardiac muscles, glands

Somatic: Skeletal muscle

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14
Q

Raynaud disease

A

Excessive stimulation following emotion stress/exposure to cold
Chronic vasoconstriction
Fingers and toes become ischemic –> could kill cells in long term
Therefore important for responses to be inducible

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15
Q

Hypothalamus - functions

A

Control internal organs via ANS and pituitary gland
Regulates behavioural patterns, circadian rhythms and sleep/wake cycles
Controls body temp
Regulates eating and drinking behaviour

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16
Q

Endocrine system - main organs

A

Hypothalamus
Pituitary
Adrenal glands

HPA axis - controls other organs in endocrine system

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17
Q

Types of hormones

A

Circulating hormones - distant target cells

Local hormones (paracrines and autocrimes)

  • Paracrine hormones - nearby target cell
  • Autocrine hormones - same target cell
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18
Q

Mechanism of action of lipid-soluble hormones

A
  1. Lipid soluble hormone diffuses into cell
  2. Activated receptor-hormone complex alters gene expression
  3. Newly formed mRNA directs synthesis of specific proteins on ribosomes
  4. New protein alters cell’s activity
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19
Q

Mechanism of action of water-soluble hormones

A
  1. Binding to receptor activates G protein which activates adenylate cyclase
  2. Activated adenyl cyclase converts ATP to cAMP
  3. cAMP serves as a second messenger to activate protein kinases
  4. Activated protein kinases phosphorylate other enzymes
  5. Phosphorylated enzymes catalyse reactions that produce physiological responses
  6. Phosphodiesterase inactivates cAMP
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20
Q

Parts of the adrenal gland

A

From superior to inferior:
Capsule
Adrenal cortex
Adrenal medulla

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21
Q

Enhancing the alarm response

A

Pre-ganglionic neuron joins to post-ganglionic neurons
Modified post-ganglionic neurons act as secretory cells - secretes epinephrine and norepinephrine into bloodstream when stimulated

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22
Q

Adrenal medulla - hormones, stimulated by, principal actions

A

Hormones: Epinephrine (adrenaline) and norepinephrine
Stimulated by: ACh from sympathetic pre-ganglionic neurons
Principal actions: Enhance sympathetic autonomic alarm response

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23
Q

Adrenal cortex - hormones, stimulated by, principal actions

A

A:
Hormone: Mineralo-corticoids (e.g. aldosterone)
Stimulated by: Increased K+ and angiotensin II in blood
Principal action: Increase blood Na+ and water and decrease blood K+ –> increased blood V and pressure

B:
Hormone: Glucocorticoids (e.g. cortisol)
Stimulated by: ACTH from pituitary, which is stimulated by CRH from hypothalamus
Principal actions: Resistance reaction to stress, dampens inflammation and depresses immune responses

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24
Q

What do the hypothalamus and pituitary gland regulate

A

Development
Metabolism
Homeostasis

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25
Portal system between hypothalamus and pituitary gland
Capillaries - portal vein - capillaries
26
Negative feedback effects on pituitary gland
Elevated cortisol inhibits release of ACTH by anterior pituitary corticotrophs (cortisol --> anterior pituitary) Elevated cortisol inhibits release of CRH by hypothalamic neurosecretory cells (cortisol --> hypothalamus)
27
Resistance reaction: Actions and consequences of glucocorticoids - Protein breakdown
Increase protein breakdown mainly in muscle fibres | Amino acids released into bloodstream may be used for synthesis of new proteins and ATP production
28
Resistance reaction: Actions of glucocorticoids - Gluconeogenesis
Liver cells convert some amino acids or lactic acid to glucose, which neurons and other cells can use for ATP production
29
Resistance reaction: Actions of glucocorticoids - Lipolysis
Breakdown of triglycerides and release of fatty acids from adipose tissue into blood
30
Resistance reaction: Actions of glucocorticoids - Resistance to stress
Increased glucose and ATP combat stresses, e.g. exercise, fasting, fright, temp extreme
31
Resistance reaction: Actions of glucocorticoids - Vasoconstriction
Blood vessels become more sensitive to hormones that cause vasoconstriction --> rise in blood pressure
32
Resistance reaction: Actions of glucocorticoids - Anti-inflammatory
Inhibit white blood cells that participate in inflammatory responses (to limit tissue damage by them) Retards tissue repair and slow wound healing
33
Resistance reaction: Actions of glucocorticoids - Immune depression
High glucocorticoid conc depress immune responses | Used therapeutically following organ transplants to retard graft rejection
34
Fight-or-flight response vs resistance reaction
Fight-or-flight is a faster response and only lasts a short while, whereas resistance reaction is slower and lasts longer (stage 2)
35
Fight-or-flight response
Immediate burst Initiated by nerve impulses from hypothalamus to sympathetic division of ANS Adrenal medulla involvements (epinephrine and NE)
36
Resistance reaction
Slower, longer lasting Associated with hypothalamus - pituitary - adrenal cortex Initiated in large part by hypothalamic releasing hormones Corticosteroid (cortisol) production
37
The stress response
Sympathetic autonomic activation (stage 1) Mobilise resources for immediate physical activity Glucose and oxygen consumption Alertness and activity Reduce tissue damage (stage 2) Ward off danger or flee!
38
Links between neuroendocrine and immune systems
Neuroendocrine ---hormones (e.g. cortisol)---> immune Neuroendocrine ---autonomic nerves---> immune Immune ---cytokines (immune hormones)---> neuroendocrine
39
Short-term remedial action
Threat system arousal: - Blood (energy) - Muscle (motor) - Vigilance (sensory) Dampen unnecessary: - Digestion - Immunity
40
Types of stresses
Eustress (acute): - Prepares us to meet certain challenges - Helpful, beneficial Distress (chronic): - Associated with undesirable events - Potentially harmful
41
How is the spinal cord connected to the brain
Through the foramen magnum of the occipital bone | Encircled by bones of vertebral column
42
What does PNS consist of
All nervous tissue outside the CNS | e.g. nerves, ganglia, sensory receptors
43
What is a nerve
A bundle of hundreds to thousands of axons plus associated CT and blood vessels that lie outside the brain and spinal cord
44
Number of cranial and spinal cords
12 pairs of cranial nerves emerge from brain | 31 pairs of spinal nerves emerge from spinal cord
45
What are ganglia
Small masses of nervous tissue, consisting primarily of neuron cell bodies located outside of the brain and spinal cord Closely associated with cranial and spinal nerves
46
What are enteric plexuses
Extensive networks of neurons located in walls of organs of GI tract
47
What is a sensory receptor
A structure of the nervous system that monitors changes in internal or external environment
48
Nervous system - functions (3)
Sensory function Integrative function Motor function
49
Nervous system - sensory function
Sensory receptors detect internal or external stimuli | This sensory info is then carried into the brain and spinal cord through cranial and spinal nerves
50
Nervous system - integrative function
Processes sensory info by analysing it and making decisions for appropriate responses - known as integration
51
Nervous system - motor function
Once sensory info is integrated, the nervous system may elicit an appropriate motor response by activating effectors through cranial and spinal nerves
52
Nervous tissue is comprised of what types of cells
Neurons and neuroglia, which combine in a variety of ways in diff regions of the nervous system
53
Neurons - electrical excitability
The ability to respond to a stimulus and convert it into an AP
54
What is a stimulus
Any change in the environment that is strong enough to initiate an AP
55
What is an AP
An electrical signal that propagates along the surface of the membrane of a neuron
56
Parts of a neuron
Cell body Dendrites An axon
57
Types of neurons
Multipolar neurons (most common neuron in brain and spinal cord) Bipolar neurons Unipolar neurons
58
Dual innervation
Most organs have dual innervation - receive impulses from both sympathetic and parasympathetic neurons
59
Cholingergic neurons
Release ACh
60
Where is ACh stored
Stored in synaptic vesicles, released by exocytosis
61
Adrenergic neurons
Release NE
62
Where is norepinephrine stored
Stored in synaptic vesicles, released by exocytosis
63
Receptor agonist
A substance that binds to and activates a receptor, in the process mimicking the effect of a natural neurotransmitter / hormone
64
Receptor antagonist
A substance that binds to and blocks a receptor --> prevents a natural neurotrasmitter or hormone from exerting its effect
65
Hypothalamus - composed of a dozen or so nuclei in which four major regions?
Mammilary region - most posterior part of hypothalamus Tuberal region - widest part of hypothalamus Supraoptic region - superior to optic chiasm Preoptic region - anterior to supra optic region
66
Hormones: Down-regulation and up-regulation
Down-regulation: If hormone is present in excess, number of target-cell receptors may decrease. Makes target cell less sensitive to a hormone Up-regulation: If hormone is deficient, number of target-cell receptors may increase. Makes target cell more sensitive to a hormone
67
Most common type of endocrine hormone
Circulating hormones - pass from secretory cells that make them into interstitial fluid and then into blood
68
Local hormones
Act locally on neighbouring cells or on the same cell that secreted them without first entering the bloodstream Usually inactivated quickly
69
Types of lipid-soluble hormones
``` Steroid hormones - derived from cholesterol Thyroid hormones (T3 and T4) - synthesised by attaching iodine to tyrosine Nitric oxide (NO) - hormone and neutransmitter ```
70
Types of water-soluble hormones
Amino hormones - synthesized by decarboxylating and modifying certain amino acids Peptide hormones and protein hormones - amino acid polymers Eicosanoid hormones - derived from arachidonic acid (fatty acid)
71
Water-soluble vs lipid-soluble hormones - free?
Most water-soluble hormones circulate in watery blood plasma in a 'free' form Most lipid-soluble hormone molecules are bound to transport proteins
72
Lipid-soluble hormones: Transport proteins - functions
Make lipid-soluble hormones temporarily water-soluble --> increases solubility in blood Retard passage of small hormone molecules through filtering mechanism in kidneys --> slows rate of hormone loss in urine Provide a ready reserve of hormone, already present in bloodstream
73
The responsiveness of a target cell to a hormone depends on...
Hormone's conc in blood Abundance of target cell's hormone receptors Influences exerted by other hormones
74
Hormones - permissive effect
Where actions of some hormones on target cells require a simultaneous or recent exposure to a second hormone
75
Hormones - synergistic effect
Where effect of two hormones acting tgt is greater or more extensive than effect of each hormone acting alone
76
Hormones - antogonistic effect
Where one hormone opposes actions of another hormone
77
The release of most hormones occur in...
Short bursts, with little or no secretion between bursts
78
Hormone secretion is regulated by...
Signals from nervous system Chemical changes in blood Other hormones
79
Most hormones work via ____ feedback
Negative feedback, but a few operate via positive feedback
80
Infundibulum
Attaches pituitary gland to hypothalamus
81
Anterior vs posterior pituitary
Anterior: accounts for ~75% of weight of gland, composed of epithelial tissue Posterior: composed of neural tissue
82
Stressor
Any stimulus that produces a stress response
83
Stress response is controlled by..
The hypothalamus
84
Stages of the stress response
1. An initial fight-or-flight response (alarm response) 2. Extended alarm response 3. A slower resistance reaction, and eventually 4. Exhaustion
85
Resistance stage and stressor
Resistance stage helps body continue fighting a stressor long after the fight-or-flight response This is why heart continues to pound for several mins even after the stressor is removed
86
Stress response - exhaustion
Due to resources of body eventually becoming depleted they can't sustain the resistance stage Prolonged exposure to high levels of cortisol and other hormones
87
Adrenergic receptors
Bind both norepinephrine and epinephrine
88
Autonomic tone
The balance between sympathetic and parasympathetic activity
89
Autonomic tone - regulation
Regulated by hypothalamus, which typically turns up sympathetic tone at the same time it turns down parasympathetic tone and vice versa
90
Why are effects of sympathetic stimulation longer lasting and more widespread than effects of parasympathetic stimulation
Sympathetic post-ganglionic axons diverge more extensively --> many tissues activated simultaneously ACh esterase quickly inactivates ACh, but NE lingers in synaptic cleft for a longer period Epinephrine and NE secreted into blood from adrenal medullae intensify and prolong responses caused by NE
91
Parasympathetic responses (SLUDD and 'three decreases')
``` Salivation Lacrimnation Urination Digestion Defecation ``` Decreased heart rate Decreased diameter of airways Decreased diameter of pupils
92
Aldosterone
Major mineralocorticoid Regulates homeostasis of Na+ and K+ (mineral ions) Helps adjust blood pressure and volume Promotes excretion of H+ in urine --> removes acids from body --> prevents acidosis
93
Corticotropin-releasing hormone (CRH)
Promotes release of ACTH from anterior pituitary --> flows into blood --> stimulates glucocorticoid secretion
94
Adrenal glands - vascular?
Highly vascularised
95
Adrenal medulla
Modified sympathetic ganglion of ANS Cells lack axons and form clusters around large blood vessels Secrete hormones - epinephrine and NE
96
Cytokines
Small protein hormones that stimulate or inhibit many normal cell functions, e.g. cell growth and differentiation
97
Synaptic transmission - steps
1. AP arrives at pre-synaptic axon terminal 2. V-gated Ca2+ channels open on pre-synaptic terminal 3. Ca2+ causes synaptic vesicles to fuse to the cell membrane and release neurotransmitters via exocytosis 4. Neurotransmitter diffuses across synaptic cleft 5. Neurotransmitter binds to receptors on post-synaptic cell membrane 6. Ligand-gated ion channels open on post-synaptic membrane and Na+ flows into post-synaptic cell 7. Post-synaptic potential reaches threshold and fires an AP 8. Nerve impulses continue to propagate
98
What is multiple sclerosis
A disease that occurs due to destruction of myelin sheaths --> slows down propagation of nerve impulses
99
Multiple sclerosis - symptoms
Vary widely depending on amount of nerve damage and which nerve are affected May experience long periods of remission without any new symptoms Lose ability to walk independently or at all Numbness or weakness in one of more limbs - usually occurs on one side of body at a time Electric-shock sensations with certain neck movements Tremor, lack of coordination or unsteady gait Effects of visions - partial or complete loss, double vision Slurred speech, fatigue, dizziness, tingling, pain in parts of body
100
Connection of anterior and posterior pituitary to hypothalamus
Anterior: via hypophyseal portal system (vascular connection) Posterior: via hypothalamic-hypophyseal tract (neural connection)
101
Anterior and posterior pituitary - response to...
Anterior: releasing and inhibiting hormones from ventral hypothalamus Posterior: directly to hypothalamic neurons
102
Hypophyseal portal system
A vascular arrangement in which blood flows from one capillary bed in the hypothalamus to another capillary bed in the anterior pituitary without going through the heart in its journey
103
Kidneys and sympathetic activation - steps
1. Sympathetic nerve activation (as a result of fight/flight response) 2. Increase in arteriole resistance --> pressure changes 3. Baroreceptors sense change in pressure 4. Juxtaglomerular cells in kidney release renin into blood 5. Renin acts on angiotensin --> cleaved to angiotensin I via renin --> cleaved to angiotensin II via ACE 6. Angiotensin II causes vasoconstriction, increases water retention and stimulates formation of aldosterone
104
If cells in a particular organ don’t respond to water-soluble hormone prolactin, the most likely reason is…
The cells lack the prolactin surface receptor
105
What occurs most rapidly when in a situation of immediate alarm
Sympathetic nerve signals affect various body functions
106
What is produced by hypothalamus to control the anterior pituitary
Releasing and inhibiting hormones
107
Resistance reaction: Responses
Increased glucose, fatty acids, amino acids Sensitised vessels Reduce inflammation Immune suppression

MEDSCI 142 (9 decks)

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